1. Field of Invention
The present invention relates to a multistage valve variable valve lift apparatus, a multistage variable valve lift system, and an engine including the same, and more particularly, to a multistage valve variable valve lift apparatus, which is capable of implementing a plurality of valve lift modes, and an engine including the same.
2. Description of Related Art
An internal combustion engine makes power by drawing fuel and air into a combustion chamber and burning the fuel and the air. Intake valves are actuated by a camshaft in order to intake the air, and the air is drawn into the combustion chamber while the intake valves are open. In addition, exhaust valves are operated by the camshaft, and a combustion gas is expelled from the combustion chamber while the exhaust valves are open.
However, an optimal operation of the intake valves and the exhaust valves depends on the rotational speed of the engine. That is, an appropriate lift or valve opening/closing time depends on the rotational speed of the engine. As such, in order to implement the appropriate valve operation depending on the rotational speed of the engine, research has been undertaken on a variable valve lift (VVL) apparatus in which cams driving the valves is designed to have a plurality of shapes or the valves operate at different lifts according to the number of rotations of the engine.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.